Mechanical
Housing Material Aluminum Alloy
Load Cell Type Strain Gauge
Capacity 20 kg
Dimensions 55.25x12.7x12.7 mm
Mounting Holes M5 (Screw Size)
Cable Length 550 mm
Cable Size 30 AWG (0.2mm )
Cable - no. of leads 4
Non-Repeatability 0.05 % FS
Creep (per 30 minutes) 0.1 % FS
Temperature Effect on Zero (per 10°C) 0.05 % FS Temperature Effect on Span (per 10°C) 0.05 % FS
Zero Balance ±1.5 % FS
Input Impedance 1130±10 Ohm
Output Impedance 1000±10 Ohm
Insulation Resistance (Under 50VDC) ≥5000 MOhm
Excitation Voltage 5 VDC
Compensated Temperature Range -10 to ~+40 °C Operating Temperature Range -20 to ~+55 °C
Safe Overload 120 % Capacity
Ultimate Overload 150 % Capacity
Glossary
Capacity
The maximum load the load cell is designed to measure within its specifications.
Creep
The change in sensor output occurring over 30 minutes, while under load at or near capacity and with all environmental conditions and other variables remaining constant.
FULL SCALE or FS
Used to qualify error - FULL SCALE is the change in output when the sensor is fully loaded. If a particular error (for example, Non-Linearity) is expressed as 0.1% F.S., and the output is 1.0mV/V, the maximum non-linearity that will be seen over the operating range of the sensor will be 0.001 mV/V. An important distinction is that this error doesn’t have to only occur at the maximum load. If you are operating the sensor at a maximum of 10% of capacity, for this example, the non-linearity would still be 0.001mV/V, or 1% of the operating range that you are actually using.
Hysteresis
If a force equal to 50% of capacity is applied to a load cell which has been at no load, a given output will be measured. The same load cell is at full capacity, and some of the force is removed, resulting in the load cell operating at 50% capacity. The difference in output between the two test scenarios is called hysteresis.
Excitation Voltage
Specifies the voltage that can be applied to the power/ground terminals on the load cell.
In practice, if you are using the load cell with the PhidgetBridge, you don’t have to worry about this spec.
Input Impedance
Determines the power that will be consumed by the load cell. The lower this number is, the more current will be required, and the more heating will occur when the load cell is powered. In very noisy environments, a lower input impedance will reduce the effect of Electromagnetic interference on long wires between the load cell and PhidgetBridge.
Insulation Resistance
The electrical resistance measured between the metal structure of the load cell, and the wiring. The practical result of this is the metal structure of the load cells should not be energized with a voltage, particularly higher voltages, as it can arc into the
PhidgetBridge. Commonly the load cell and the metal framework it is part of will be grounded to earth or to your system ground.
Maximum Overload
The maximum load which can be applied without producing a structural failure.
Non-Linearity
Ideally, the output of the sensor will be perfectly linear, and a simple 2-point calibration will exactly describe the behaviour of the sensor at other loads. In practice, the sensor is not perfect, and Non-linearity describes the maximum deviation from the linear curve.
Theoretically, if a more complex calibration is used, some of the non-linearity can be calibrated out, but this will require a very high accuracy calibration with multiple points.
Non-Repeatability
The maximum difference the sensor will report when exactly the same weight is applied, at the same temperature, over multiple test runs.
Operating Temperature
The extremes of ambient temperature within which the load cell will operate without permanent adverse change to any of its performance characteristics.
Output Impedance
Roughly corresponds to the input impedance. If the Output Impedance is very high, measuring the bridge will distort the results. The PhidgetBridge carefully buffers the signals coming from the load cell, so in practice this is not a concern.
Rated Output
Is the difference in the output of the sensor between when it is fully loaded to its rated capacity, and when it’s unloaded. Effectively, it’s how sensitive the sensor is, and
corresponds to the gain calculated when calibrating the sensor. More expensive sensors have an exact rated output based on an individual calibration done at the factory.
Safe Overload
The maximum axial load which can be applied without producing a permanent shift in performance characteristics beyond those specified.
Compensated Temperature
The range of temperature over which the load cell is compensated to maintain output and zero balance within specified limits.
Temperature Effect on Span
Span is also called rated output. This value is the change in output due to a change in ambient temperature. It is measured over 10 degree C temperature interval.
Temperature Effect on Zero
The change in zero balance due to a change in ambient temperature. This value is measured over 10 degree C temperature interval.
Zero Balance
Zero Balance defines the maximum difference between the +/- output wires when no load is applied. Realistically, each sensor will be individually calibrated, at least for the output when no load is applied. Zero Balance is more of a concern if the load cell is being interfaced to an amplification circuit - the PhidgetBridge can easily handle
enormous differences between +/-. If the difference is very large, the PhidgetBridge will not be able to use the higher Gain settings.
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